Rehydrating temp for Ale vs Lager yeast

[golfandbrew]

I recently had a discussion with someone about rehydrating lager yeast. It's been a long time since I brewed a lager so I thought the forum may be able to help me out.

I know fermentis and the like will recommend lower temps when rehydrating lager yeasts but other sources (books, forum articles, ect) never seem to make this distinction.

My thinking was that since you are just rehydrating the yeast the warmer temps of 30-40 C wouldn't hurt and would actually be ideal. This is assuming you are not taking the yeast straight from the fridge and into the warm water. My other assumption is that you are still letting the rehydrated yeast cool to fermentation temps before pitching.

I did take a packet of lager yeast and split between two jars to rehydrate. One jar at 35 C and one at 25 C. The 35 C water rehydrated the yeast much better. I did not have wort to pitch these into to see any difference in fermentation or flavor. Hoping the forum may be able to offer some insight as to the impact, if any, of redyrating lager yeast at a higher temps of 30-40C?

Cheers!

 

[Tall_Yotie]

The temperature of fermentation is for off-flavors and activity, so I doubt that will be an issue when you come to re-hydrating yeast. Granted I never re-hydrate yeast as that is usually done only to confirm that the yeast is still viable.

 

[Silver_Is_Money]

Fermentis advises that W-34/70 lager yeast should be rehydrated in 70 to 77 degree F. water, and for SO-4 ale yeast they advise 77-84 degrees F.

 

[Lefou]

I always use warm or room-temperature water to re-hydrate. If you're pressed for time an 11.5 gram packet put in .5 liters of water can be hydrated at ambient, ready to pitch in thirty minutes or less for a 5gal/18.9l batch.
I did this two days ago with Abbaye ale yeast that was set to expire. The packet was vacuum sealed and was a fallback option when my liquid yeast failed to energize in an overnight starter. The liquid yeast was less than two months old and dead, but the sealed dry yeast was still good almost a year later.
Go figure.
I woke in the morning before work, re-hydrated, and pitched at about 6AM. The krausen was noticeable in six hours, and going full blast twelve hours later.

 

[tooldudetool]

I always assume the yeast manufacturer has done far more testing than I ever could, so I just follow their recommendations.. that being said, I would be shocked if you could taste a difference in the finished beer.